<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>jQuery</title>
</head>

<body>
    <ul>
        <li>我是LI1</li>
        <li>我是LI2</li>
        <li>我是LI3</li>
    </ul>
</body>
<script src="./js/jquery.js"></script>
<script>
    $("li").click(function (params) {
        $(this).css("background", "red")
    })
</script>

</html>